Science Inventory

Relative contributions of select multigeneration products to chamber SOA formed from photooxidation of a range (C10-C17) of n-alkanes under high NOx conditions

Citation:

Docherty, K., W. Preston, R. Yaga, M. Jaoui, T. Riedel, J. Offenberg, T. Kleindienst, AND M. Lewandowski. Relative contributions of select multigeneration products to chamber SOA formed from photooxidation of a range (C10-C17) of n-alkanes under high NOx conditions. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 244(1):117976, (2021). https://doi.org/10.1016/j.atmosenv.2020.117976

Impact/Purpose:

This study identifies several potential marker compounds for secondary organic aerosol produced from the photooxidation of n-alkanes under urban conditions. These markers may be used to identify when the atmospheric oxidation of volatilized fuels or automobile emissions are contributing to ambient PM2.5 concentrations.

Description:

A series of chamber experiments was conducted to investigate the change in the relative contribution of multigeneration reaction products to total secondary organic aerosol (SOA) mass across a range of parent n-alkanes (C10-C17) that has a high potential for SOA formation in urban atmospheres. Contributions of select first, second, and higher generation products to SOA was investigated using online speciation by an aerosol mass spectrometer and varied substantially across the range of investigated alkanes. As expected, the presence of first-generation species in SOA is limited primarily by volatility with small contributions at the low end of the investigated n-alkane range and increasing gradually as the number of carbons is increased. The formation of lower volatility second and higher generation nitrate-containing species, in contrast, appears to be mechanistically limited leading to lower average contributions of organic nitrates to OA as the size of the parent n-alkane is increased. The impact of increased water vapor concentrations similarly varied with the size of the parent alkane with diminished effect as both alkane carbon number and generation number increased. The largest impacts of water, however, were between dry (~3%) and slightly humid (~14%) with little change observed at higher relative humidities.